This invention relates to a method and device for capturing sound for use in recording phonorecords, compact disks, and the like having improved three-dimensional imagery during playback.
Since the development of dual-channel or xe2x80x9cstereoxe2x80x9d transmission systems, audio system designers have sought ways to improve upon the dimensionality of source recordings. There are currently two schools of thought on how to achieve this goal: Algorithmic manipulation; and binaural recording. In the algorithmic approach, elaborate processing techniques are utilized including, for example, phase shifting and EQ delays so as to create the illusion of height and depth. The quality of the output signal in this approach, however, is directly dependent on the quality of the input data. High quality three-dimensional imagery can therefore only be achieved if high quality input data is utilized. As those skilled in the art will recognize, however, this is generally not the case in conventional recording techniques. Moreover, it has been found that even the slightest over-processing may sufficiently distort the output signal so as to render it displeasing to listeners.
Binaural recording techniques, on the other hand, have shown greater promise as a method for improving source recording dimensionality. A historical account of binaural sound applications and processing techniques may be found in the article xe2x80x9cA History of Binaural Soundsxe2x80x9d by John Sunier, published in the March, 1986 edition of Audio Maqazine. As discussed therein, from approximately 1936 to 1983, binaural devices and processing techniques remained relatively unchanged. In operation, a mannequin or similar dummy head was utilized as a source recording device having a pair of microphones separated by a baffle so as to form right and left channels.
The 1980""s brought variations in this traditional device including, for example, full ear canals which created a redundant complication. Namely, the use of a full ear canal in the sound recording device coupled with the listener""s own full ear canal, was found to greatly distort the received signal. Other variations included, for example, the use of multiple microphones. This approach, however, has been found most suitable only in those situations where multiple speakers are also being used such as, for example, in 360xc2x0 surround sound theaters found in theme parks and the like. Other variations on the binaural approach may also be found, for example, in U.S. Pat. No. 3,985,960, issued to Wallace, Jr.; U.S. Pat. No. 4,074,084, issued to van den Berg; U.S. Pat. No. 4,388,494, issued to Schone et al.; U.S. Pat. No. 4,393,270, issued to van den Berg; U.S. Pat. No. 4,741,035, issued to Genuit; and U.S. Pat. No. 5,105,822, issued to Stevens et al. Each of these patents discloses a method of sound reproduction which utilizes a binaural approach.
While these variations show marked improvements over traditional binaural recording techniques, they nonetheless result in sound recordings which lack the desired height/depth components necessary to achieve full three-dimensional imagery. Applicant has found that the prior art devices lack this component because of a fundamental misunderstanding regarding the way in which humans hear. While traditional devices were developed based on the understanding that humans hear primarily with their ears, Applicant has found in practice that the human body, and in particular, a body vibration component plays an important role. If properly harnessed, this vibration component will result in sound recordings having markedly improved source dimensionality.
Consequently, a need exists for a sound capturing method and device which utilizes both direct sound and body vibration information for use in source recordings so as to provide improved three-dimensional imagery during playback.
It is an object of the present invention to overcome the limitations of the prior art by providing a sound capturing method and device which mimics the human sound capturing process.
A more specific object of the present invention is the provision of a sound capturing method and device for detecting and combining vibration information and direct sound information received at respective first and second locations on a body portion, the locations being in sufficient proximity to one another such that a sound wave will reach each location at substantially the same time. If the locations cannot be in sufficient proximity to allow for the sound wave to reach each location at substantially the same time, the signal received at either location may be processed or time-delayed such that sound waves are recorded from each location at substantially the same time.
Yet another more specific object of the present invention is the provision of a sound capturing method and device which detects and combines vibration information and direct sound information through the use of at least one crystal microphone/condenser microphone pair affixed to a vibratory body, the components being positioned in sufficient proximity to one another such that a sound wave will reach the crystal microphone and the condenser microphone at substantially the same time. Again, if the crystal microphone cannot be placed in sufficient proximity to the condenser microphone to allow for a sound wave to reach each location at substantially the same time, the signal received at either location may be processed or time-delayed such that sound waves are recorded from each location at substantially the same time.
Still another object of the present invention is the provision of a sound capturing method and device which detects body vibration information through the use of a vibratory body having a torso portion which includes a pair of plates adapted to vibrate over a full range of frequencies without significant oscillation and combines the same with direct sound information.
It is a further object of the present invention to provide a recording which includes combined vibration information and direct sound information fixed in a tangible medium, both the vibration information and the sound information being generated in response to a sound wave, the vibration information corresponding to the vibrational frequency of a vibratory body at a first location and the direct sound information generated directly from the sound wave at a second location, the second location being in sufficient proximity to the first location such that the sound wave will reach each location at substantially the same time. If the locations cannot be in sufficient proximity to allow for the sound wave to reach each location at substantially the same time, the signal received at either location may be processed or time-delayed such that sound waves are recorded from each location at substantially the same time.
In accordance with the invention, a sound capturing method is provided which includes the steps of detecting vibration information from a body portion at a first location to generate a first signal corresponding to a vibrational frequency of the body portion in response to a received sound wave. Direct sound information is further detected from the body portion at a second location to generate a second signal corresponding to a frequency of the received sound wave. The second location is in sufficient proximity to the first location such that a sound wave will reach each location at substantially the same time. Alternatively, the signal received at either location may be processed or time-delayed such that sound waves are recorded from each location at substantially the same time.
In a preferred embodiment, the vibration information is detected through the use of a crystal microphone and the direct sound information is detected through the use of at least one electret microphone. The at least one electret microphone is preferably, but not necessarily, co-located with the crystal microphone. Once the vibration information and the direct sound information has been detected, it is combined through the use of a mixer. In a stereo version, vibration information and direct sound information is detected and combined from each side of the vibratory body so as to provide a dual channel output.
In carrying out the above method, a sound capturing device is further provided for recording a phonorecord such as an electromagnetic cassette, an LP, a compact disc, or the like. In its simplest form, the sound capturing device comprises a body portion having a first microphone such as a crystal microphone affixed thereto at a first location for generating a first signal corresponding to a vibrational frequency of the body portion in response to a received sound wave. At least one secondary microphone, such as a condenser microphone, is affixed to the body portion at a second location for generating a second signal corresponding to a frequency of the received sound wave. In keeping with the invention, the second location is in sufficient proximity to the first location such that the sound wave will reach each location at substantially the same time. Alternatively, the signal received at either location may be processed or time-delayed such that sound waves are recorded from each location at substantially the same time. As noted above, the crystal microphone and the at least one secondary microphone are preferably, but not necessarily, co-located. The resultant first and second signals may be combined through the use of a mixer.
In a preferred embodiment of the sound recording device, the body portion is integral and is geometrically configured to simulate a human head and torso. The torso portion includes a pair of outwardly extending plates each having a plurality of ribs of varying mass which are adapted to vibrate over a range of audio frequencies without significant oscillation.
In a stereo version of the invention, the body portion of the above-described sound recording device includes a right side and a left side which may be delineated, for example, by an internal baffle. A first crystal microphone is affixed to the right side of the body portion at a first location and a first condenser microphone is affixed to the right side of the body portion at a second location. Still further, a second crystal microphone is affixed to the left side of the body portion at a first location and a second condenser microphone is affixed to the left side of the body portion at a second location. The crystal microphone/condenser microphone pairs on each side of the body portion are disposed relative to one another such that a sound wave will reach each of the microphones making up the pair at substantially the same time. Alternatively, the signal received at either location may be processed or time-delayed such that sound waves are recorded from each location at substantially the same time. A mixer may also be provided for combining the vibration and direct sound information on respective sides of the body portion.
In a preferred stereo embodiment, multiple (two or more) condenser microphones may be affixed in groups to the right and left sides of the head portion at respective third, fourth, etc. locations. The groups of condenser microphones are disposed relative to their corresponding crystal microphone (right or left side) such that a sound wave will reach the group of condenser microphones and the corresponding crystal microphone at substantially the same time. Alternatively, the signal received at either location may be processed or time-delayed such that sound waves are recorded from each location at substantially the same time. Again, in keeping with the invention, the groups of condenser microphones are preferably, but not necessarily, co-located with their corresponding crystal microphone.
These and other objects, features and advantages of the present invention may be more readily apparent from a review of the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.